A. Field of the Invention
The Invention is a rotary wing aircraft featuring two or more laterally spaced-apart vectored thrusters that may be tilted between a first and a second position. The vectored thrusters may be equipped with adjustable horizontal vanes to direct selectably the flow of air from the vectored thrusters. The vectored thrusters also may be equipped with controllable-pitch propellers to selectably control the amount of thrust generated by each vectored thruster. The vectored thrusters, vanes and controllable-pitch propellers can be configured selectably to provide additional lift and to allow the rotary wing aircraft to reach higher ultimate speeds. The vectored thrusters, vanes and controllable pitch propellers also provide increased control power. A rotary wing aircraft equipped with the vectored thrusters, vanes and controllable pitch propellers of the Invention can be configured as part of an aircraft control system to provide greater control moments in roll and yaw than a rotary wing aircraft that does not include vectored thrusters, vanes and controllable pitch propellers. The Invention also may be applied to a compound aircraft.
B. Description of the Related Art
A conventional helicopter is a rotary wing aircraft including at least one main rotor and a means to overcome the torque response of the rotor. A compound aircraft includes all of the elements of a helicopter and also includes elements of a fixed-wing aircraft, such as a wing. As used in this document, the term “rotary wing aircraft” means a helicopter or compound aircraft.
The forward speed of a rotary wing aircraft is limited by advancing blade compression effects and retreating blade stall. A rotary wing aircraft may be equipped with an additional thrust mechanism, such as a propeller in a ducted fan, referred to herein as a “thruster.” A conventional thruster may provide additional forward thrust to the rotary wing aircraft. The additional forward thrust may allow the rotary wing aircraft to reach higher ultimate speeds by postponing advancing blade compression effects and retreating blade stall. The additional forward thrust also may allow the aircraft to achieve lower fuel consumption and increased range. The use of a thruster can complicate the operation of the rotary wing aircraft in hover. To successfully hover, a rotary wing aircraft utilizing a thruster must be able to eliminate the effects of the forward thrust provided by the thruster.
The pilot of a conventional helicopter has only limited controls. The controls available for a conventional helicopter having a single main rotor and a tail rotor are:
Throttle—The pilot can control the amount of power supplied to the rotor blades and to the tail rotor.
Collective pitch—The pilot contemporaneously can change the pitch of all main rotor blades by an equal amount using the collective pitch control, also known as the ‘collective.’ Contemporaneously changing the pitch angle of all main rotor blades increases or decreases the lift supporting the helicopter. Increasing the collective and the power will cause the helicopter to rise. Decreasing the collective and the power will call the helicopter to descend.
Cyclic pitch—The pilot may use the cyclic pitch control, also known as the ‘cyclic,’ to cause the pitch angle of the main rotor blades to change differentially as the main rotor rotates through 360 degrees. The cyclic pitch control is used to control the pitch and roll of the helicopter. For example, increasing the pitch angle of a rotor blade when the rotor blade is retreating toward the rear of the helicopter and decreasing the pitch angle when the rotor blade is advancing toward the front of the helicopter will cause the main rotor plane of rotation to tilt forward and hence will cause the helicopter to move forward.
Yaw control—For a conventional helicopter having a tail rotor mounted on a boom, a pedal-operated yaw control changes the pitch of the tail rotor blades so that the tail rotor presents more or less force countering the torque response of the rotating main rotor. The pitch of the tail rotor blades therefore controls the yaw of the conventional helicopter having a tail rotor.
A conventional tandem-rotor helicopter, for example the Boeing CH47 Chinook, is equipped with two rotors and dispenses with a tail rotor. The pilot of a tandem-rotor helicopter operates controls identical to those of a single-rotor helicopter. The tandem-rotor helicopter achieves control equivalent to that of a single-rotor helicopter by applying either uniform or differential cyclic and collective pitch to each of the tandem rotors.
For either a single rotor or tandem rotor conventional helicopter and for a particular throttle setting, there is only one combination of trim control settings for the collective, cyclic and yaw controls to achieve any particular desired trimmed condition of the helicopter. The pilot of the conventional helicopter therefore has few control options.
It is desirable to provide a conventional helicopter with the benefits of thrusters to improve speed, range and fuel economy while retaining the benefits of the rotor in hover and low speed operation. It is also desirable to provide a conventional helicopter with increased control moments for yaw, pitch and roll. The prior art does not teach the apparatus of the Invention.